1. Field of the Technology
The technology of the present disclosure relates to a modified wheat protein isolate and its use in food systems.
2. Background of the Technology
Wheat flour is ideal for bread making since the storage proteins of wheat form a strong, cohesive dough that retains gas bubbles, such as carbon dioxide produced by yeast during rising of bread products, to produce light baked products. The wheat proteins may be isolated from wheat flour by removing starch and albumins/globulins by gently working the dough under a stream of water. After washing, a rubbery ball remains comprising the wheat gluten proteins, which are known as “vital wheat gluten”. Traditionally, gluten proteins have been classified into four families according to their solubility: 1) albumins, which are soluble in water or dilute salt solutions and are coagulated by heat; 2) globulins, which are insoluble in pure water but soluble in dilute aqueous salt solutions and insoluble in concentrated aqueous salt solutions; 3) prolamins, which are soluble in aqueous alcohol; and 4) glutelins, which are soluble in dilute acid or bases, detergents, or dissociating or reducing agents, such as urea or 2-mercaptoethanol, respectively.
The prolamins are considered to be unique to the seed of cereals and other grains or grasses. The prolamins have been given different names in different cereals, such as: gliadin in wheat, avenins in oats, zeins in maize, secalins in rye, and hordein in barley. The gliadins and glutenins of wheat are the storage proteins of the wheat endosperm. Gluten can be described as having a bimodal distribution between gliadin and glutenin. Gluten composition is a major factor in determining wheat dough mixing strength and processing characteristics.
Gliadin, or the gliadin fraction of gluten, has a low ionic strength and excellent film forming properties. Gliadin is insoluble in water; however, its solubility may be modified with the addition of a surfactant and/or adjustment of the pH by acidification. Typical acids suitable for solubilizing Gliadin include citric acid, malic acid, lactic acid, oxalic acid, tartaric acid, ascorbic acid, and acetic acid. Gliadin may absorb up to twice its weight of water.
Glutenin, or the glutenin fraction of gluten, is highly elastic and rubbery and is also resistant to shear. Glutenin is insoluble in alcohol and neutral water, however, its solubility may be modified with the addition of a surfactant and/or adjustment of the pH. The protein structure of glutenin is stabilized by interchain disulfide bonds.
Vital wheat gluten is approved by the U.S. Food and Drug Administration as Generally Recognized as Safe (GRAS) under 21 C.F.R. §184.1322 for use as a dough strengthener, formulation aid, nutrient supplement, processing aid, stabilizer and thickener, surface finishing agent, and texturizing agent at levels not to exceed current good manufacturing practice. Vital wheat gluten is defined as a viscoelastic gluten that is extensible when hydrated. As used herein, the term “extensible” means capable of being stretched without tearing.
Through further removal of non-protein constituents, the protein content of vital wheat gluten can be increased. The functional properties of this protein can be modified through the use of acids, reducing agents, phosphates, enzymes, and combinations thereof to convert the proteins to a “wheat protein isolate”. The wheat protein isolates have been used in bakery systems for a variety of functions including increasing dough extensibility, decreasing dough mix time, increasing sheeting ability, and increasing protein content, as well as for increasing laminating performance of dough systems. Wheat protein isolates may be added to bread doughs to modify various characteristics, such as rise, dough strength, and dough chewiness. Wheat protein isolates may also be used as an additive to non-wheat flours, such as almond flour, to maintain the gluten-like characteristics, typically associated with wheat flours, in flours that lack gluten.
Food bars, such as, breakfast bars, granola bars, cereal bars, nutrition bars, meal supplements bars, rice cakes, candy bars, protein bars, and energy bars, have become an increasingly popular form of nutrition due, in part, to their small size, portability, and ability to be rapidly consumed. Typically, food bars comprise food particulates and/or powders, and a food-grade binder, which binds bar ingredients into a coherent mass that may be shaped into the desired form. In general, food binders must effectively bind the food ingredient system in such a way that the bar is readily consumable, i.e., exhibit acceptable taste, mouth-feel, texture, density, ease of biting; while still maintaining acceptable shelf life. Common food binders traditionally used in the food industry include corn syrups, molasses, starches, evaporated cane juice, other carbohydrate based binders, egg products such as egg proteins, vital wheat gluten, and glycerin.
While general food-grade binder products are available, there are few products on the market that are suitable for use as binders that do not increase the sweetness of these food systems. In addition, nearly all of these available binders are carbohydrate based and are used in a concentration of greater than 15% by weight.